Liquid inks, e.g., aqueous and solvent-based inks, require drying time after deposition on a substrate. Factors such as ink composition, substrate characteristics and environmental conditions affect the rate of drying. If sufficient time is available, liquid inks may be permitted to dry without additional actions being taken. However, some situations, e.g., high throughput printing, require that liquid inks dry in an accelerated timeframe.
Some printing systems use heaters, lamps, blowers, etc. to accelerate drying. For example, carbon filament lamps positioned adjacent the substrate pathway after the print zone, i.e., where the printed image is formed, are used to dry liquid inks. Known systems have used carbon filament lamps oriented perpendicular to the process direction of cut sheet media and roll fed media, i.e., oriented in the cross process direction. In the case of cut sheet media, a vacuum transport moves the media from the marking/printing module to an area underneath a set of infrared (IR) lamps to dry the aqueous ink on the media. Depending on the source and type of lamp, the intensity along the length of the lamp may change significantly. Such non-uniformity along the length of a lamp can cause as much as 5-10° C. variation in the cross-process direction. In addition to the non-uniform lamp output, a ray trace of the foregoing lamp arrangement, as depicted in FIG. 3, demonstrates cross-process uniformity challenges as well. These issues are discussed in greater detail below.
Moreover, lamp issues may be more or less prevalent depending on the manufacturer of the lamp. For example, one manufacturer's emitter is a multi-stranded carbon filament under spring tension, while another manufacturer's emitter is a spiral filament that may touch the glass and produce carbon residue on the glass. This residue may contribute to light attenuation and/or create cross-process cold spots.
Furthermore, conventional drying systems provide all media sizes the same power, i.e., an 8.5″×11″ media long edge feed leaves 3.4″ of transport conveyor exposed to irradiance and overheating of the outboard silicone transport belt, while the same system would have minimal exposed transport conveyor when drying an 8.5″×14″ media long edge feed. In short, cross-process orientation of lamp arrays is incapable of accounting for varying paper sizes.
The present disclosure addresses a system and method for drying liquid ink with a size adjustable lamp array which maintains a consistent temperature profile throughout most of the drying zone of a printer system.